Occipital Plate With Angled Screw Opening

ABSTRACT

A surgical implant includes a first portion and a second portion. The first portion includes a body and connector assemblies. The body includes a posterior surface and defines a first bore defining an acute angle with respect to a first axis that is orthogonal to the posterior surface. The connector assemblies are disposed on opposing lateral sides of the body. Each connector assembly is selectively rotatable relative to the body. The second portion includes a base extending in a cephalad direction from the first portion, and an extension extending in the cephalad direction from the base. The base defines second bores configured to receive respective bone screws. The extension defines a third bore. The first bore of the body and the third bore of the extension define a second axis. The second bores are defined along a third axis orthogonal to the second axis.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/657,711, filed on Oct. 18, 2019, which claims the benefit of thefiling date of U.S. Provisional Patent Application No. 62/747,756 filedOct. 19, 2018, the disclosure of which is hereby incorporated herein byreference.

BACKGROUND Technical Field

The present disclosure relates to devices for bone fixation and, moreparticularly, to an occipital plate for cervical fixation.

Background

The occipito-cervical junction, which comprises the occiput, atlas, andaxis, represents a unique and complex interface between the cranium andthe rostral cervical spine. More than 50% of the rotation andflexion-extension of the head and neck occurs in that region. Inaddition, the osseous articulations and their ligamentous supportstructures must resist force in eight axes of rotation. These includeflexion, extension, bilateral lateral bending, bilateral rotation,distraction, and axial loading. Any surgical implants designed for usein this region must, therefore, have adequate dimensions to interfacewith the osseous structures of the spinal structures as well as havesufficient rigidity and purchase to resist these forces until bonefusion can occur. Great flexibility must be afforded to allow for themultiple anatomical variations seen in this region.

In the early 1900's occipitocervical instability and lesions located atthe occipitocervical junction were considered inoperable and terminal.Since the first description of an occipitocervical fusion by Forresterin 1927, multiple methods of fusion in this region have been described.Simple onlay bone grafts with halo immobilization; wire, pin, or hookconstructs; rigid metallic loops and rectangles fixed to the bone witheither screws or wires; and most recently, plate or rod constructs withscrews have all been described. In general, the evolution of thistechnology has focused on providing increasingly more rigid constructsto facilitate bone fusion and to minimize the need for and duration ofexternal immobilization.

A common technique for fixing occipitocervical instability is the use ofan inverted Y-shaped screw plate. Using this technique, the plate issecured to C1-C2 with transarticular screws and to the suboccipital bonewith paramedian screws. Therefore, a need exists for a simple andeffective occipital plate for cervical fixation.

SUMMARY

In accordance with an embodiment of the present disclosure, a surgicalimplant includes a first portion and a second portion. The first portionincludes a body and connector assemblies. The body includes a posteriorsurface and defines a first bore defining an acute angle with respect toa first axis orthogonal to the posterior surface. The connectorassemblies are disposed on opposing lateral sides of the body. Eachconnector assembly is selectively rotatable relative to the body. Thesecond portion includes a base extending in a cephalad direction fromthe first portion, and an extension extending in the cephalad directionfrom the base. The base defines second bores configured to receiverespective bone screws. The extension defines a third bore. The firstbore of the body and the third bore of the extension define a secondaxis. The second bores are defined along a third axis orthogonal to thesecond axis.

In an embodiment, the acute angle defined by the first bore may be about15 degrees.

In another embodiment, at least one of the connector assemblies may beconfigured for poly-axial movement.

In yet another embodiment, the at least one of the connector assembliesmay be configured for poly-axial movement through a cone of about 25degrees.

In an embodiment, the body of the first portion may include a mountdefining a hole.

In an embodiment, the mount may include an engaging surface protrudingradially inward of the hole.

In another embodiment, the connector assembly may include a housingdefining a slot configured to receive a spinal rod, a support configuredto support the housing and slidably engage the engaging surface of themount, and a nut configured to be coupled with the housing in order tocouple the housing to the mount of the body.

In yet another embodiment, the nut may be configured to threadablyengage the housing of the connector assembly.

In still yet another embodiment, the connector assembly may furtherinclude a radially deflectable retaining ring. At least a portion of theradially deflectable retaining ring may be configured to extend radiallyoutward from a first circular groove defined in the housing.

In still yet another embodiment, the nut may define a second circulargroove configured to receive the at least a portion of the radiallydeflectable retaining ring extending radially outward from the firstcircular groove of the housing.

In an embodiment, the support may have an annular configuration. Thesupport may define diametrically opposing recesses configured to receivethe spinal rod.

In yet another embodiment, the body may further define fourth and fifthbores adjacent the first bore. At least one of the fourth or fifth boresmay define an acute angle with respect to the first axis.

In an embodiment, at least one of the first, fourth, or fifth bores maybe surrounded by a lip.

In another embodiment, the second portion may have an inverted T-shape.

In yet another embodiment, the first portion may be symmetric about thesecond axis.

In accordance with another aspect of the present disclosure, a method ofsurgery includes mounting a bone screw to a vertebra; securing a spinalrod to the bone screw; placing an occipital plate adjacent occipitalregion of a spine; securing the spinal rod with a connector assembly ofthe occipital plate; and securing the occipital plate to the occipitalregion of the spine. In particular, the occipital plate includes a firstportion and a second portion. The first portion includes a body definingfirst bore defining an acute angle with respect to a first axis that isorthogonal to a surface of the body; and a connector assembly configuredto receive the spinal rod. The connector assembly is disposed on alateral side of the first portion. The second portion defines a secondbore. The first and second bores are arranged along a second axis;

In an embodiment, securing the occipital plate may include mounting abone screw to the occipital region of the spine through the first boreof the body.

In another embodiment, securing the occipital plate may include mountingthe bone screw to the occipital region of the spine at an angle of about15 degrees with respect to the first axis.

In yet another embodiment, securing the spinal rod with the connectorassembly may include adjusting the connector assembly in a poly-axialdirection relative to the body of the first portion.

In still yet another embodiment, securing the occipital plate mayinclude mounting a bone screw to the occipital region of the spinethrough the second bore of the second portion.

BRIEF DESCRIPTION OF THE DRAWINGS

Various preferred embodiments of the presently disclosed occipital plateare described herein with reference to the drawings:

FIG. 1 is a top view of an occipital plate in accordance with anembodiment of the present disclosure;

FIG. 2 is a front view of the occipital plate of FIG. 1;

FIG. 3 is a perspective view of the occipital plate of FIG. 1;

FIG. 4 is an exploded perspective view of the occipital plate of FIG. 1with parts separated;

FIG. 5 is a top view of the occipital plate of FIG. 1;

FIG. 6 is a cross-sectional view of the occipital plate of FIG. 5 cutalong section line 6-6 of FIG. 5;

FIG. 7 is a cross-sectional view of the occipital plate of FIG. 5 cutalong section line 7-7 of FIG. 5;

FIG. 8 is an exploded perspective view of an occipital plate inaccordance with another embodiment of the present disclosure;

FIG. 9 is a perspective view of the occipital plate of FIG. 1,illustrating use on a skull of a patient;

FIG. 10 is a side cross-sectional view of the occipital plate of FIG. 9cut along section line 10-10 of FIG. 9; and

FIG. 11 is an enlarged cross-sectional view of the indicated area ofdetail of FIG. 10.

DETAILED DESCRIPTION

The presently disclosed occipital plate will now be described in detailwith reference to the drawings in which like reference numeralsdesignate identical or corresponding elements in each of the severalviews. However, it is to be understood that the disclosed embodimentsare merely exemplary of the disclosure and may be embodied in variousforms. Well-known functions or constructions are not described in detailto avoid obscuring the present disclosure in unnecessary detail.Therefore, specific structural and functional details disclosed hereinare not to be interpreted as limiting, but merely as a basis for theclaims and as a representative basis for teaching one skilled in the artto variously employ the present disclosure in virtually anyappropriately detailed structure. As shown in the drawings and asdescribed throughout the following description, and as is traditionalwhen referring to relative positioning on an object, the terms“proximal” and “trailing” may be employed interchangeably, and should beunderstood as referring to the portion of a structure that is closer toa clinician during proper use. The terms “distal” and “leading” may alsobe employed interchangeably, and should be understood as referring tothe portion of a structure that is farther from the clinician duringproper use. In addition, the term “cephalad” is used in this applicationto indicate a direction toward a patient's head, whereas the term“caudad” indicates a direction toward the patient's feet. Further still,the term “medial” indicates a direction toward the middle of the body ofthe patient, whilst the term “lateral” indicates a direction toward aside of the body of the patient (i.e., away from the middle of the bodyof the patient). The term “posterior” indicates a direction toward thepatient's back, and the term “anterior” indicates a direction toward thepatient's front.

With reference to FIGS. 1 and 2, an occipital plate in accordance withan embodiment of the present disclosure is generally shown as occipitalplate 100. The occipital plate 100 includes a first portion 110 and asecond portion 210. The first and second portions 110, 210 define alongitudinal axis “Y-Y” extending in cephalad and caudad directions. Theoccipital plate 100 is symmetric about the longitudinal axis “Y-Y.” Theoccipital plate 100 may be formed of titanium alloy. Bone screws “B”(FIG. 9) and spinal rods “R” (FIG. 10) may be utilized to secure theoccipital plate 100 to anatomical structures of the patient. Referencemay be made to U.S. Pat. Nos. 9,295,494 and 9,339,307, the entirecontents of each of which are incorporated herein by reference, for adetailed description of the construction of bone screws and spinal rods.

The first portion 110 defines bores 112 configured to receive respectivebone screws. One of the bores 112 is positioned on the longitudinal axis“Y-Y” such that one of the bores 112 is centered and interposed betweentwo adjacent bores 112. Each bore 112 is surrounded by a lip 114 formedof titanium alloy. The bone screws received in the bores 112 may includethreads formed of a titanium alloy such as, e.g., Ti-6Al-4V.Alternatively, the bore 112 may include complementary threads forforming a secure attachment with the bone screw.

Each bore 112 defines an acute angle a with respect to an axis “O-O”(FIG. 6) orthogonal to a posterior surface 116 (FIG. 6) of the firstportion 110. For example, the acute angle a may be in a range of about10 and 30 degrees. In an embodiment, the acute angle a may be in a rangeof about 10 and 20 degrees. In another embodiment, the acute angle a maybe about 15 degrees, i.e., each bore 112 may define an angle β of about105 degrees with respect to the posterior surface 116. Defining the bore112 at such an angle facilitates insertion of the bone screw during asurgical procedure. In particular, such a configuration enables the bonescrew to accommodate e.g., the curvature of the skull “S” (FIG. 10), ofthe patient. In addition, the bone screw inserted at such an angle mayfurther inhibit the bone screw from backing out of and separating fromthe first portion 110. Optionally, the first portion 110 may furtherdefine slots 150 dimensioned to receive a band (not shown), as describedin U.S. Pat. No. 9,675,386, the entire contents of which areincorporated herein by reference, that is configured to further securethe occipital plate 100 to the anatomical structure of the patient. Forexample, adjacent bores 112 may be separated by the slot 150.

With reference now to FIGS. 3 and 4, the first portion 110 includesconnector assemblies 130 disposed laterally outward of the bores 112. Inparticular, the connector assemblies 130 are disposed on opposing sidesof the first portion 110. The first portion 110 is symmetric about thelongitudinal axis “Y-Y.” The first portion 110 further includes a mount128 on each lateral side thereof. Each mount 128 defines a hole 127therethrough. The mount 128 includes an engaging surface 128 aprotruding radially inward of the hole 127 for poly-axial engagementwith the connector assembly 130.

With continued reference to FIG. 4, the connector assembly 130 isconfigured to securely support a spinal rod “R” (FIG. 11) therein. Theconnector assembly 130 is configured for poly-axial movement. Inparticular, each connector assembly 130 is movable through a cone in arange of about 10° and 30°. In an embodiment, each connector assembly130 is movable through a cone in a range of about 20° and 30°. Inanother embodiment, each connector assembly 130 is movable through acone of about 25°. The connector assembly 130 includes a housing 132having a head portion 134 defining a slot 138 dimensioned to receive thespinal rod “R” therein, and a base portion 136 including threads 136 a.The connector assembly 130 further includes a support 140 adjustablysupporting the housing 132 on the mount 128, and a nut 146 configured tothreadably engage the threads 136 a on the base portion 136 of thehousing 132 to secure the housing 132 to the mount 128. In particular,the support 140 has an annular configuration configured to receive thebase portion 136 therethrough. The support 140 is slidably adjustable onthe engaging surface 128 a of the mount 128 to enable poly-axialmovement of the housing 132 on the mount 128. The support 140 has anannular wall 142 defining diametrically opposing recesses 144dimensioned to receive the spinal rod “R” therein. The adjustablymounted housing 132 may be secured to the mount 128 by threadablycoupling the nut 146 to the base portion 136. In particular, poly-axialmovement of the housing 132 with respect to the mount 128 is inhibitedwhen a set screw is inserted and tightened in the housing 132 onto thespinal rod “R” seated on the support 140.

With reference now to FIG. 5, the occipital plate 100 further includes asecond portion 210 that extends in a cephalad direction from the firstportion 110. The second portion 210 includes a base portion 220 definingan axis “X-X” orthogonal to the longitudinal axis “Y-Y” (FIG. 4). Thebase portion 220 further defines bores 214 along the axis “X-X.” One ofthe bores 214 is positioned along the longitudinal axis “Y-Y” andinterposed between the other bores 214. Each bore 214 is surrounded by alip 216 in a manner described with respect to the lip 114 (FIG. 1). Inaddition, the base portion 220 further defines slots 218 interposedbetween adjacent bores 214. The slot 218 may be configured to receive aband to further secure the occipital plate 100 to an anatomicalstructure of the patient. In addition, the base portion 220 may be cutor bent along the slot 218 to a suitable configuration in order totailor the occipital plate 100 to the particular surgical procedure orthe patient. The second portion 210 further includes an extensionportion 240 extending in the cephalad direction from the base portion220. The extension portion 240 defines a bore 222 disposed along thelongitudinal axis “Y-Y.” The bore 222 may be surrounded by a lip 224 ina manner described hereinabove with respect to the lip 114 (FIG. 1).

In use, the clinician initially prepares the occipital bone and thevertebrae. The clinician may form insertion holes in, e.g., osseoustissue, by preparing the surface with a burr or other like instrumentand then an awl to start the hole. The clinician may secure bone anchorsin vertebral bodies in order to secure spinal rods “R” (FIG. 10) to thevertebrae. Once the spinal rods “R” have been placed with the boneanchors, the clinician may perform posterior fixation of the occipitalplate 100 to the occipital region of the spine. Based on the surgicalprocedure and the patient, the connector assemblies 130 (FIG. 7) may berotated relative to the mount 128 in a poly-axial direction. The spinalrods “R” are placed in the respective connector assemblies 130 and aresecured to the connector assemblies 130 by respective set screws (notshown). Thereafter, bone anchors are inserted through the bores 112 atan angle relative to a plane defined by the plate to secure theoccipital plate 100 to the patient. Prior to securing the occipitalplate 100 to the patient, the clinician may manipulate the secondportion 210 by, for example, cutting or bending along, e.g., the slots218, of the base portion 220. Thereafter, additional bone screws may beinserted through the bores 214 and/or 222 of the second portion 210, asneeded, to secure the occipital plate 100 to the patient.

With reference now to FIG. 8, a connector assembly in accordance withanother embodiment of the present disclosure is generally shown as aconnector assembly 330. Parts of an occipital plate 300 including theconnector assembly 330 substantially identical to the parts of theoccipital plate 100 will not be described herein to avoid obscuring thepresent disclosure in unnecessary detail. The connector assembly 330includes a housing 332, a support 140, a retaining ring 350, and a nut346. While the connector assembly 130 (FIG. 1) is secured to the mount128 by threadably coupling the base portion 136 of the housing 132 withthe nut 146, the connector 330 includes the retaining ring 350 that isradially deflectable. The housing 332 includes a head portion 334configured to receive a spinal rod “R”, and a base portion 336configured to extend through the support 140 and the hole 127. The baseportion 336 defines a circular groove 336 a dimensioned to receive theretaining ring 350 therein such that at least a portion of the retainingring 350 extends radially outward when positioned in the groove 336 a.The nut 346 defines a circular groove 346 a configured to receive theportion of the retaining ring 350 extending radially outward from thecircular groove 336 a of the base portion 336 a. Under such aconfiguration, the retaining ring 350 may be compressed and released inorder to couple the nut 346 to the base portion 336 of the housing 332when securing the housing 332 to the mount 128. The method of use of theoccipital plate 300 including the connector assembly 330 issubstantially identical to the use of the occipital plate 100, and thus,will not be described herein.

Persons skilled in the art will understand that the structures andmethods specifically described herein and shown in the accompanyingfigures are non-limiting exemplary embodiments, and that thedescription, disclosure, and figures should be construed merely asexemplary of particular embodiments. For example, it is contemplatedthat the rod receiving portion of the housing may include a taper lockfor locking the spinal rod relative to the housing, rather than a setscrew design as shown. A suitable taper lock configuration may beadapted from the taper lock design shown in International PatentApplication Publication No. WO 2009/055407, the entire contents of whichare incorporated herein by reference. It is to be understood, therefore,that the present disclosure is not limited to the precise embodimentsdescribed, and that various other changes and modifications may beeffected by one skilled in the art without departing from the scope orspirit of the disclosure. Additionally, the elements and features shownor described in connection with certain embodiments may be combined withthe elements and features of certain other embodiments without departingfrom the scope of the present disclosure, and that such modificationsand variations are also included within the scope of the presentdisclosure. Accordingly, the subject matter of the present disclosure isnot limited by what has been particularly shown and described.

1. An occipital bone plate comprising: a first portion including: a body including a posterior surface, the body defining a first bore; and a mount having an engaging surface; a second portion including: a base extending in a cephalad direction from the first portion and defining a second bore; and an extension extending in the cephalad direction from the base and defining a third bore, the first and third bores defining a first axis and the second bore defining a second axis orthogonal to the second axis; and a connector assembly including a support poly-axially adjustable on the engaging surface of the mount.
 2. The occipital bone plate of claim 1, wherein the first bore defines a third axis at an acute angle with respect to an orthogonal axis to the posterior surface.
 3. The occipital bone plate of claim 2, wherein the acute angle is about 15 degrees.
 4. The occipital bone plate of claim 1, wherein the connector assembly is configured for poly-axial movement through a cone of about 25 degrees.
 5. The occipital bone plate of claim 1, further comprising two connector assemblies and two mounts.
 6. The occipital bone plate of claim 1, wherein the mount defines a hole, the engaging surface protruding radially inward of the hole.
 7. The occipital bone plate of claim 1, wherein the connector assembly includes a housing defining a slot configured to receive a spinal rod, the support is configured to support the housing, and a nut configured to be coupled with the housing in order to couple the housing to the mount of the body.
 8. The occipital bone plate of claim 7, wherein the nut is configured to threadably engage the housing of the connector assembly.
 9. The occipital bone plate of claim 7, wherein the connector assembly further includes a radially deflectable retaining ring, at least a portion of the radially deflectable retaining ring configured to extend radially outward from a first circular groove defined in the housing.
 10. The occipital bone plate of claim 9, wherein the nut defines a second circular groove configured to receive the at least a portion of the radially deflectable retaining ring extending radially outward from the first circular groove of the housing.
 11. The occipital bone plate of claim 7, wherein the support has an annular configuration, the support defining diametrically opposing recesses configured to receive the spinal rod.
 12. The occipital bone plate of claim 1, wherein at least one of the bores includes a lip configured to deform.
 13. An occipital bone plate comprising: a first portion having a first bore hole and a first slot; and a second portion having a second bore hole and a second slot, wherein the occipital bone plate is bendable along the slots located in the second portion.
 14. The occipital bone plate of claim 13, further comprising a connector assembly polyaxially engaged with a mount of the first portion.
 15. The occipital bone plate of claim 14, wherein the connector assembly includes a slot for receiving a spinal rod.
 16. The occipital bone plate of claim 13, further comprising two connector assemblies polyaxially engaged with respective mounts of the first portion.
 17. A method of surgery comprising: bending an occipital bone plate, wherein the bending of the occipital bone plate occurs along a slot formed in either a first portion or a second portion of the occipital bone plate; placing the bent occipital bone plate on an occipital bone; inserting a first fastener through a first hole in the first portion and into the occipital bone; and inserting a second fastener through a second hole in the second portion and into the occipital bone.
 18. The method of claim 17, further comprising the step of attaching a spinal rod to the occipital bone plate.
 19. The method of claim 18, wherein the attaching step includes placing the spinal rod in a slot of a connector assembly.
 20. The method of claim 19, wherein the placing step includes moving the connector assembly with respect to the occipital bone plate. 